Devices for reading data from a data storage disc, such as a CD-ROM drive for reading data from a CD-ROM, are typically designed such that the data storage disc is first placed in a disc caddy or a sliding tray. After the data storage disc is so placed, the disc caddy or sliding tray conveys the data storage disc to a driving mechanism and continues to support the data storage disc until the driving mechanism begins rotating the data storage disc at which time data is read from the data storage disc.
A typical driving mechanism for driving the rotation of the data storage disc includes a motor-driven chuck and spindle assembly where the chuck holds the data storage disc by retaining a center hole in the data storage disc. After the chuck has retained the data storage disc using the center hole, the chuck and spindle assembly rotate thereby causing rotation of the data storage disc. As the data storage disc is rotating, a data head capable of reading from the disc is positioned along a radius to read data from data tracks on the data storage disc, and a focus actuator in communication with the data reading head continuously adjusts the distance between the data reading head and the data storage disc so that the data reading head remains focused on the data and can successfully read the data from the data storage disc even if the data storage disc is not rotating perfectly.
The above-described data reading device, and driving mechanism thereof, has several disadvantages. For example, regardless of whether a disc caddy or sliding tray is used to convey the data storage disc to the driving mechanism, the spindle and chuck assembly, as well as the motor to drive same, must be positioned either above or below the data storage disc so that the data storage disc can be engaged by the chuck and rotated. This arrangement limits the minimum height to which the data reading device can be minimized. It is often desirable to minimize the area occupied by a data reading device because, among other reasons, such devices are presently widely used in portable computer applications.
Further, the center hole of the data storage disc, and the data storage disc itself, necessarily have design tolerances and these design tolerances can hinder the efficient operation of the data reading device. For example, an imperfect center hole, even within acceptable design tolerances, can cause the data storage disc to periodically vibrate as the data storage disc is rotated by the chuck and spindle assembly of the drive mechanism. Such vibration causes the data reading head to oscillate along the sled as it works to follow a specific data track. If the vibration of the data storage disc is adequately severe, the vibration can cause the data reading head to fail to follow the specific data track.
Moreover, if the data storage disc is chucked at even only a slight angle relative to the plane of the data reading head, the data storage disc will tend to oscillate above the head as it rotates. Such an oscillation will cause the focus actuator to also oscillate as it works to keep the data reading head focused on the data. If the oscillation of the data storage disc is adequately severe, the oscillation of the data storage disc can prevent the focus actuator from maintaining the head focused on the data.
Additionally, the data reading device necessitates initial physical contact of the data storage disc with either a disc caddy or a sliding tray, and subsequent physical contact of the data storage disc with a chuck. Physical contact with the data storage disc can cause the data storage disc to become scratched or otherwise damaged and cause some of the data stored on the data storage disc to become inaccessible.
The above-discussed disadvantages are also generally applicable to data write devices.
For the foregoing and other reasons, there is a need for an improved drive mechanism for rotating data storage media, such as a data storage disc. The present invention provides a novel drive mechanism which alleviates the problems discussed above.